Research On Dynamic Error Sources Analysis And Modeling Of Coordinate Measuring Machines

Modern manufacturing technology has put forward more increasing requirement of speedand accuracy on Coordinate Measuring Machines (CMMs) and high speed has become a newtrend in CMM technology. However, with the increasing speed, the dynamic accuracy willdecrease since dynamic errors will have a great impact on the accuracy and act as a barrier tothe measuring cycle time. In this paper, the impact of velocity parameters on dynamicperformance of CMMs is studied.This thesis presents the category of dynamic errors about CMMs in detail.The errors ofCMMs due to axis motion and vibration are studied and a brief discussion on different methodsfor reducing the dynamic errors of CMMs is proposed.There are several factors that influencethe sensitivity of the machines components for dynamic errors and the effects of these errors onthe probe position.Thesis categorizes them as factors related to the CMM configuration,thecomponents propertied and the dynamic load on the CMM.Thus the more efficient designmethods for reducing the dynamic errors of CMMs are provided.Mainly the method developed here for estimating the dynamic errors consists of theidentification of the parametric errors and calculation of the their effects on the measuring errorat probe position,using a kinematic model,including of dynamic parametric errors modeling,onedegree of freedom vibration error of air-bearing modeling and dynamic probing error modeling.To illustrate the dynamic errors mentioned in the previous modeling some FEM emulations ofMoving Bridge CMM will be studied,including geometry parameter modeling byPro/E,mechanical analysis,FEM analysis by Ansys and MSC.nastran.It is noted the FEMmodel is not same as the geometry parameter model.Thus the model simply is a crucialprocess.The emulation results can be used as a tool for the CMMs design evaluation and errorscompensation.